Reduction in risk of cardiovascular disease (CVD) through dietary change has considerable potential for a beneficial impact on public health. On a population basis, moderation of both lipid profiles and blood pressure can be accomplished readily with a prudent diet. Nevertheless, individual response to dietary impact on CVD risk factors varies widely, presumably as a result of genetic differences. In particular, Blacks who constitute a subpopulation with documented increased risk of morbidity and mortality from CVD would disproportionately benefit from interventions designed to maximize the impact of dietary change tailored to individual genetic makeup. Therefore, study of the influence of diet on CVD risk factors, along with enhanced understanding of the genetic components involved, would greatly potentiate chronic disease interventions. We will test the hypothesis that the responsiveness of major and emerging CVD risk factors to changes in diet composition clusters within families depending on genetic susceptibility factors. We propose to identify two-generational family lines in Blacks with elevated low density lipoprotein-C (LDLC) in probands and intervene on this population with a controlled diet contrasting an established heart healthy regimen with a typical American one. Concomitant rigorous genetic, anthropometric, and behavioral evaluation will provide data with which to analyze individual differences in response to consistent dietary intake. In Specific Aim 1, Black, two-generational, families will be recruited and provided interventional diets designed to reduce (or not) LDL-C and blood pressure. In Specific Aim 2, we will identify non-genetic predictors of CVD risk factor response through extensive assessments of baseline behavioral characteristics, anthropometric features, and metabolic factors. In Specific Aim 3, the underlying genetic factors that predispose to response (or the lack of) to dietary interventions will be identified through the examination of polymorphisms in candidate genes and the identification of susceptibility loci by linkage analyses. In Specific Aim 4, interactions between diet, CVD risk factor response and genetic factors will be dissected through measures of potential mediating metabolic pathways. The study proposed here is expected to identify the link between healthy diet, genetic factors and their underlying biological mechanisms. This information will guide the design of future dietary and lifestyle interventions to combat CVD.